Lubricant compositions



United States Patent O 3,251,773 LUBRICANT COMPOSITIONS Reigh C. Gunderson, Midland, Mich., assignor to The Dow Chemical Company, Midland, Mich., a corporation of Delaware No Drawing. Filed Sept. 27, 1963, Ser. No. 311,996 11 Claims. (Cl. 25249.6)

This invention relates to lubricants and hydraulic fluids which are flame resistant and'to the preparation of-such compositions. More particularly, the present invention relates to flame-resistant lubricants and hydraulic fluids which contain meta-oriented dibromo phenyl ether as a flame inhibitor.

It is well known that certain halogenated aromatic compounds are flame-resistant due to the halogen atoms present in such compounds. Polychlorinated dip'henyl ethers containing more than three atoms of chlorine per molecule are flame-resistant, as disclosed in US. Patent 2,165,813 to Prutton. Halogenated aromatic ethers have also been suggested as suitable additives to motor fuels (top cylinder lubricants), as disclosed in US. Patent 2,214,768 to Lincoln. Although such halogenated aromatic compounds have desirable flame-resistant properties, these compounds are usually not compatible with.

organic lubricants and hydraulic fluids. Flame-resistance is achieved only at the expense of other properties. For example, the additive may precipitate out of the composition at low temperatures, or may even cause coagulation of the entire fluid within a given range of operating temperatures. When chlorinated diphenyl ethers are used, greater amounts are necessary to achieve the same fire-retardant effect which results. with a given amount of the corresponding brominated ether.

It has now been found that meta-oriented dibromo phenyl ether mwd) can be added to silcones, mineral oils and crankcase oils to impart flame-resistant properties without adversely affecting other desirable properties of these oils (such as oxidation resistance, viscosity-temperature relationships, pour point, flash point, lubricity and air solubility). By the term meta-oriented it is meant that at least one bromine atom is in the meta position relative to the ether oxygen atom. Thus, meta,meta-dibromo, meta,orthodibromo and meta-para-dibromo phenyl ethers are all meta-oriented dibromo phenyl ethers.

Only an amount of meta-oriented dibromo phenyl ether which is suflicient to impart the desired degree of flame-resistance is required. Amounts of meta-dibromo phenyl ether of up to about 35-40 percent by weight (based upon the total weight of the final composition) may be used. No special techniques are required for adding the meta-dibromo phenyl ether to the fluid which is to be flame proofed. Ordinarily, the meta-dibromo phenyl ether is merely added to the fluid and mechanically blended by physically mixing or stirring. Other inert materials may be mixed with the meta-dibromo phenyl ether. Amounts of meta-dibromo phenyl ether of from about 5 percent to 35 percent by weight are generally sufficient to improve the flame-resistance of any hydraulic fluid or lubricant which is not a solid at temperatures of from about 80 to 300 F.

Suitable lubricants and hydraulic fluids to which the P ICC meta-dibromo phenyl ether may be added includehave a freezing point below 0 F., since conventional additives tend to precipitate out at lower temperatures. Although organopolysiloxanes are normally highly flameresistant without additives, the incorporation of metadibromo phenyl-ether into such compositions has been,

found to further improve the flame resistant properties of these silicones.

Typical silicones which may be blended with metadibromo phenyl ether according to this invention include the dimethyl silicone fluids with the repeating structural unit CH S'1O \C s as well as silicones which contain varying amounts of phenyl groups in place of the methyl groups (Dow Corning 550), or those silicone-s which contain varying amounts of chlorophenyl groups in place of methyl groups.

As mentioned previously, the meta-oriented dibromo phenyl ether does not precipitate out of the lubricant and hydraulic compositions at low temperatures. For example, using three different silicone fluids, it was found that a 10 percent (weight) concentration of meta-oriented dibromo phenyl ether remained in the silicone fluids at temperatures of from -50 to -56 F. over a 72 hour period, whereas the para-dibromo phenyl ether precipitated at 54 F. using the same concentration in the same silicone fluids. Ortho-dibromo phenyl ether is not soluble in these silicones. Similar results are obtained in mineral oils when the meta-dibromo phenyl ether and the para-dibromo phenyl ether are compared at temperatures of from -38 to 42 F. using concentrations of 10 percent and 25 percent by weight of the additives.

The following examples are subitted for the purpose of illustration only and are not to be construed as limiting the scope of the invention in any way.

Examples I-XI mately 0.8" by 0.1") was saturated with the resulting composition and the saturated wick was passed through the flame (top of the inner cone) of a Bunsen burner until the wick ignited. The wick was passed through the flame at a rate of about 60 passes per minute. The number of passes to obtain ignition with and without TABLE 1 Concentration Number of of Meta-Ori- Passes ented Dibromo Example Base Fluid Phenyl Ether Number (Percent. by Base Blended Weight) in Fluid Fluid Base Fluid Dow Corning 550-.. 25 24 53 (lo 10 24 29 Dow Corning 560--. 25 8 18 o 10 8 10 Dow Corning XF 25 13 33 4039." Shell 20W-20 crank- 25 6 14 case oil. do 10 6 9 Bis(phenoryphcnyl) 25 7 22 ether. do 10 7 8 Deep-dewaxed super 25 7 16 refined mineral oil (type MLO 60-294). .do 10 7 11 Dow Corning 550 (obtained from the Dow Corning Corp.) is a clear, low viscosity silicone oil with a flash point of 575 F. (ASTM D92), a viscosity of 100 to 150 centistokes at 77 F. and a refractive index at 25 C. (Na D line) of 1.4935. Dow Corning 560 is a light straw-colored silicone fluid (primarily used for hydraulic systems) containing chlorophenyl groups with-- in the organopolysiloxane polymer with a flash point of 550 -F., a viscosity of 75 centistokes at 77 F., a pour point below -85 F. and a specific gravity of 1.076 at F. Dow Corning XF 4039 is a silicone fluid with a viscosity of 47 centistokes at 25 C., a flash point of 535 F., a freezing point of -85 F., a specific gravity of 1.021 at 25 C. and a refractive index (Na D line) of 1.4596. Thus meta-oriented dibromo phenyl ether used was a liquid isomer mixture in which at least 50 percent of the molecules contain a bromine atom in the meta position (relative to the ether linkage) on one or both of the phenyl rings. Compositions with a higher meta content (85 percent or greater) may be used at lower temperatures without precipitating out of the lubricant or hydraulic fluid.

I claim as my invention:

1. A flame-resistant fluid selected from the group consisting of a hydraulic fluid and a lubricant containing a minor amount sufficient to impart flame resistance of meta-dibromo phenyl ether of the formula 2. The composition of claim 1 wherein the fluid is an organopolysiloxane.

3. The composition of claim 1 wherein the fluid is a mineral oil-based hydraulic fluid.

4. The composition of-claim 1 wherein the fluid is a poly(-phenoxyphenyl) ether.

5. The composition of claim 1 wherein the fluid is bis(phenoxyphenyl) ether.

6. The composition of claim 1 wherein the fluid is petroleum-based crankcase oil.

7. Flame-resistant silicone polymer fluids containing up to 40 percent by weight of meta-dibromo phenyl ether of the formula as an active fire-retarding agent dissolved therein.

8. The composition of claim 7 wherein the silicone fluid contains phenyl substituents in the silicone polymer.

9. The composition of claim 7 wherein the silicone fluid contains chlorophenyl substituents in the silicone polymer.

10. A method of inhibiting the production of flame in a system subject to frictional forces which comprises contacting said system with the composition of claim'l.

I 11. A flame-resistant silicone polymer fluid characterized by the presence of at least one chlorophenyl group within the silicone polymer molecules and containing from about 10 to 40 percent by weight of metadibromo phenyl ether as an active fire-retarding agent dissolvedinthe silicone polymer fluid.

References Cited by the Examiner UNITED, STATES PATENTS 2,137,784 11/1938 Prutton et a1. 252-54- 2,258,219 10/1941 Rochow 25254 X 2,877,182 3/1959 May 252-49.6 3,006,852 10/1961 Barnum et a1. 252-52 3,048,545 8/1962 Critchley et a1. 25249.6 X

DANIEL E. WYMAN, Primary Examiner. P. P. GARVIN, Assistant Examiner. 

1. A FLAME-RESISTANT FLUID SELECTED FROM THE GROUP CONSISTING OF A HYDRAULIC FLUID AND A LUBRICANT CONTAINING A MINOR AMOUNT SUFFICIENT TO IMPART FLAME RESISTANCE OF META-DIBROMO PHENYL ETHER OF THE FORMULA
 2. THE COMPOSITION OF CLAIM 1 WHEREIN THE FLUID IS AN ORGANOPOLYSILOXANE. 